With all due respect, this is a new bug that popped up two weeks ago. Prior to these reports, there were no dev resources assigned to fix it.
So they have to pull resources off a current assignment, diagnose the issue, fix it, compile the fix into the upcoming patch build, and ensure that the fix doesn't break anything else. I don't know what their patching approval process looks like, but I bet patch content is assigned at least a week or two in advance.
Given that the game typically has one patch every 1-2 weeks, a 2-4 week gap between bug identification and fix seems actually be pretty good. I've never heard of a game company that drops everything to fix a minor game bug for a small population of players - especially since this doesn't prevent anyone from playing the game, just delays this one quest line until the fix.
I know all the players stuck behind this bug are frustrated. However, all anyone here can tell you is "please be patient."